NEWPORT BEACH, Calif.—Nissan Motor Co.'s reputation as a top auto maker once was cast in the horsepower, speed and style of its "Z" sports cars. No more. The Japanese company wants its image defined by a coming electric car that drives itself.

Nissan's decision to highlight its foray into autonomous, zero-emission driving at a lavishly staged program here says a lot about how the auto industry is rapidly changing in the...